The EVGA 01G-P3-1380-KR GeForce GTX 460 SSC+ is a factory overclocked card.
The minimum power supply requirement is one that is 450 Watts or greater and with a combined +12 Volt rails current rating of 24 Amps or greater. The PSU should also have at least two available 6-pin PCI-E power connectors. Wattage is not the most important specification, it's the DC output current on the combined +12 Volt rail(s) as well as good voltage regulation and low electrical noise and ripple. Reliability is also a major concern.
The replacement power supply should adhere to the standard ATX form factor with the following dimensions: 6" Wide X 3.5" Tall X 5.5" Deep.
What is your budget for the power supply unit?
Here's one I would recommend:Antec EarthWatts Green EA-430D
for $49.99 at newegg.com